Installation of inflatable occupant restraint systems, generally known as “airbags,” as standard equipment in all new vehicles has intensified the search for smaller, lighter and less expensive restraint systems. Accordingly, since the inflator used in such systems tends to be the heaviest and most expensive component, there is a need for a lighter and less expensive inflator.
A typical inflator includes a cylindrical steel or aluminum housing having a diameter and length related to the vehicle application whereby the propellant is contained therein. The inflator is generally provided with an internal filter comprising one or more layers of expanded metal or steel screen of varying mesh and wire diameter. Gas produced upon combustion of the propellant passes through the filter before exiting the inflator. Particulate material, or slag, produced during combustion of the propellant in a conventional system is substantially removed as the gas passes through the filter.
The conventional filter/heat sink designs formed from compressed knitted wire or expanded metals remove heat via thermal mass. However, the composition and structure of these conventional filters act to increase the weight of the filter and to reduce the uniformity and controllability of gas flow, thereby increasing ballistic variability.